Microorganisms survive step closer to Mars environment
Posted: May 27, 2001

The Red Planet. Photo: NASA/JPL
University of Arkansas researchers have moved one step closer to growing microorganisms under Mars-like conditions by suspending them in water containing dissolved matter from Mars soil simulant.

D. Ryan Ormond, Curtis R. Bekkum and Timothy Kral, associate professor of biological sciences, reported their findings this past week at the American Society for Microbiology meeting in Orlando.

"We've eliminated one factor," said Kral, bringing them one step closer to approaching conditions on Mars.

The researchers work with methanogens, microorganisms of the group Archaea. These organisms grow under anaerobic conditions, often in extreme environments, so Kral believes they may provide clues to the type of life that might be found below the surface of Mars. Methanogens can be found deep in the ocean, in the earth's crust or even in a cow's stomach, all of which are environments that might be considered harsh like the conditions found on Mars.

Two years ago, Kral became the first scientist to grow microbes under some of the conditions found on Mars. Now he and research assistants Bekkum and Ormond have refined their experiments to eliminate one factor likely not found on Mars -- a standard buffer used to keep the methanogens in suspension so they don't disintegrate.

The researchers added Mars soil simulant in varying amounts to de-ionized water, then mixed it overnight. They decanted the mixture the next day and used the liquid fraction to wash and suspend the methanogens. The suspensions were added to Mars soil simulant in sealed anaerobic tubes and incubated, then analyzed for methane metabolism, an indicator of methanogen growth.

The samples were compared to a control that was suspended in a standard sodium hydroxide buffer with bubbled carbon dioxide gas.

"We can use the liquid fraction of water mixed with soil simulant to suspend the cells, and the organisms will grow," Kral said.

The methanogens grew in the liquid fraction composed of water and simulant, although not as well as they did in the standard buffer. The researchers hypothesize that the pH, which was lower for the liquid fractions, may have reduced growth.

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